ABSTRACT
Osteoclast and osteoblast are essential for proper bone development and remodeling as well as recovery of bone fracture. In this study, we seek chemical compounds that enhance turnover of bone metabolism for promoting bone healing. First, we screen a chemical library which includes 378 compounds by using murine pre-osteoclastic RAW264.7 cells to identify compounds that promote osteoclastic differentiation. We find that two ROCK (Rho-associated coiled-coil kinase) inhibitors, HA-1077 (Fasudil) and Y-27632, enhance osteoclastogenesis. Subsequently, we identify that these two compounds also increase osteoblastic differentiation of MC3T3-E1 cells. Finally, our in vivo experiment shows that the local administration of ROCK inhibitors accelerate the bone healing of the rat calvarial defect.
Subject(s)
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/analogs & derivatives , Amides/pharmacology , Osteogenesis/drug effects , Protein Kinase Inhibitors/pharmacology , Pyridines/pharmacology , rho-Associated Kinases/antagonists & inhibitors , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/chemistry , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/pharmacology , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/therapeutic use , Amides/chemistry , Amides/therapeutic use , Animals , Cell Differentiation , Cell Line , Fracture Healing/drug effects , Male , Mice , Osteoblasts/cytology , Osteoblasts/drug effects , Osteoblasts/metabolism , Osteoclasts/cytology , Osteoclasts/drug effects , Osteoclasts/metabolism , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/therapeutic use , Pyridines/chemistry , Pyridines/therapeutic use , RAW 264.7 Cells , Rats , Rats, Sprague-Dawley , Skull/drug effects , Skull/injuries , Skull/metabolism , Small Molecule Libraries/chemistry , Small Molecule Libraries/pharmacology , rho-Associated Kinases/metabolismABSTRACT
This study aimed to analyze the mRNA expression and protein localization of prostaglandin I2 (PGI2) synthase (PGIS), the PGI2 receptor (IP receptor) and transient receptor potential cation channel, subfamily V, member 1 (TRPV1) in force-stimulated rat molars, toward the elucidation of the PGI2-IP receptor-TRPV1 pathway that is in operation in the pulp and possibly associated with orthodontic pain and inflammation. Experimental force was applied to the maxillary first and second molars by inserting an elastic band between them for 6-72 h. PGIS, PTGIR (the IP receptor gene), and TRPV1 mRNA levels in the coronal pulp were analyzed with real-time PCR. PGIS, IP receptor, and TRPV1 proteins were immunostained. The force stimulation induced significant upregulation of PGIS at 6-24 h, and PTGIR and TRPV1 at 6 and 12 h in the pulp. PGIS was immunolocalized in odontoblasts and some fibroblasts in the force-stimulated pulp. The IP receptor and TRPV1 immunoreactivities were detected on odontoblasts and some nerve fibers. It was concluded that PGIS, PTGIR, and TRPV1 in rat molar pulp were significantly upregulated shortly after the force application, and that the IP receptor was co-expressed on TRPV1-expressing nerves and odontoblasts. These findings suggest that the PGI2-IP receptor-TRPV1 pathway is associated with the acute phase of force-induced pulp changes involving odontoblasts and nerves.
Subject(s)
Cytochrome P-450 Enzyme System/genetics , Dental Pulp/metabolism , Gene Expression , Intramolecular Oxidoreductases/genetics , Receptors, Epoprostenol/genetics , TRPV Cation Channels/genetics , Tooth Movement Techniques , Animals , Immunoenzyme Techniques , Male , Molar , Odontoblasts/metabolism , RNA, Messenger/genetics , Rats , Rats, Wistar , Real-Time Polymerase Chain Reaction , Time Factors , Up-RegulationABSTRACT
Mineral trioxide aggregate (MTA) is a commonly used dental pulp-capping material with known effects in promoting reparative dentinogenesis. However, the mechanism by which MTA induces dentine repair remains unclear. The aim of the present study was to investigate the role of prostaglandin E2 (PGE2) in dentine repair by examining the localisation and mRNA expression levels of its transporter (Pgt) and two of its receptors (Ep2 and Ep4) in a rat model of pulpotomy with MTA capping. Ep2 expression was detected in odontoblasts, endothelial cells, and nerve fibres in normal and pulpotomised tissues, whereas Pgt and Ep4 were immunolocalised only in the odontoblasts. Moreover, mRNA expression of Slco2a1 (encoding Pgt), Ptger2 (encoding Ep2), and Ptger4 (encoding Ep4) was significantly upregulated in pulpotomised dental pulp and trigeminal ganglia after MTA capping. Our results provide insights into the functions of PGE2 via Pgt and Ep receptors in the healing dentine/pulp complex and may be helpful in developing new therapeutic targets for dental disease.
